Governments must codify regulations on silent data gathering so that users around the world can regain confidence in the use of the internet, Google's chief legal officer, David Drummond, has said.

Drummond also forcefully reiterated the company's position that it has not given the US National Security Agency (NSA) access to its servers, and that it did not know of the Prism programme before the Guardian revealed it last week.

He said that the company would continue to push to be able to publish more information about secret requests for data. "But we don't write the laws," he said.

In a Q&A session for the Guardian, Drummond said "it's high time that governments get together and decide some rules around [secret data gathering]. Remember that this is not just about the US government, but European and other governments too. It's really important that all of us give close scrutiny to any laws that give governments increased power to sift through user data."

He reiterated Google's position on Prism: "We're not in cahoots with the NSA and there is no government programme that Google participates in that allows the kind of access that the media originally reported."

A PowerPoint presentation from the NSA suggested that it had "direct" access to the systems of nine companies – Microsoft, AOL, Yahoo, Apple, Skype, PalTalk, YouTube, Facebook and Google. The companies have denied allowing such access. Google has said that it did provide a secure file transfer system for data requested by the NSA under Fisa (Foreign Intelligence Surveillance Act) orders, whose contents are secret.

Drummond said that the search firm had finally managed this year to be allowed to say how many national security letters (used by US government agencies such as the FBI and CIA) it has received demanding data on users. "We don't question that there are legitimate requests for data – in a criminal attack, for example, or a suspected terrorist attack. We simply believe there should be more transparency around the breadth of these requests." But he dodged questions on whether Google had been pushing to publish data about Fisa requests before the scandal broke.

Restating the position of many Silicon Valley companies, Drummond suggested that the news of the extent of the surveillance scheme had surprised Google too. "We didn't know [Prism] existed," he said.

He said that Google backed the work of Viviane Reding, vice-president of the European commission, , to simplify privacy laws "in a way that both protects consumers online and stimulates economic growth", insisting both were possible.

Questions posed by Guardian readers to Drummond suggested that some have lost a measure of trust in the company, and are unsure whether business data could be seized in the same way as individuals' data.

Drummond's response suggested that the company is feeling the effects of the leaks and is keen to rebuild its reputation. Asked how users would be able to tell if Google were lying, he answered: "Our business depends on the trust of our users. And I'm an executive officer of a large publicly-traded company, so lying to the public wouldn't be the greatest career move." To another user, he said: "I'm really troubled if you've lost trust in us because of this idea that we're collaborating in a broad surveillance programme. We're not."

Drummond has worked at Google since 2002, and was its first outside counsel. His history working with the firm goes back to 1998.